The scientific characterization of cell function is often approximated by studying an aggregate structure of cells or the smallest still functional multicellular preparations that retains the function of the entire organ under investigation. When it comes to the quantification of stress or strain on individual cells, technology is limited when it comes to actually measuring stress or strain at such a low force level. It is limited in the ability to impose stress or strain for example in the form of a length change (stretch) or conversely push and then to quantify the response. It is limited in the ability to attach and hold onto a single cell due to the cell's fragile nature. And, it is limited in the ability to manipulate and position the individual cell to allow it to be brought into alignment with a measurement apparatus. This is best illustrated in the case of muscle cells. Muscle function is typically carried out on multicellular intact tissue preparations. During known experimentation, isometric force, contractibility under external force or stretch (often referred to as “load”), with or without electrical stimulation, and temporal determination of membrane potential and/or internal calcium concentration are measured in a strictly controlled environment. Drawbacks of current state of the art equipment for performing measurements on single (individual) muscle cells include:                1. Since tissue preparations do not have blood circulation present, the potential for oxygen deprivation exists as the experimenter approaches the internal portion of the muscle sample. The lack of blood perfusion in isolated tissues results in potential oxygen deprivation due to an increased demand over supply resulting in hypoxia with unknown but usually negative implications on the tissue function. This is directly related to the diffusional limitation in larger intact multi-cellular tissues and whole organs and cannot be completely overcome with high oxygen tension in surrounding fluids.        2. Most known techniques require buffers and experimental reagents which are slow to diffuse toward the center of the muscle sample. Due to the lack of perfusion, experimental substances, salts and ions used to test tissue function will not readily reach all cells in larger tissues and organs, potentially yielding unreliable results and data.Microscopic analysis of intact muscle preparations is often very difficult. Although optical techniques can be used to observe cells in the outer layer of a tissue, these are also the cells that lie near the injury zone where the tissue sample was separated from the larger unit or organ. Moreover, optical techniques fail to observe and sample responses from the deeper underlying cells.        3. When employing in vivo experimentation techniques, intact organs and tissues thereof are inherently multi-cellular, leaving the uncertainty that observed behaviors and responses are partly due to complex effects resulting from the contribution of different cells and structures in the same tissues. In other words the measured response is a sum of effects of all cells and supporting structures in the sample. In the case of muscle, these also include cells such as fibroblasts, nerve cells and cells of the blood supply system in the wall of small arteries and capillaries. Also, there is significant connective tissue between the cells (matrix) that greatly influence the passive mechanical properties of a tissue.        4. Diseased muscle has a complex mixture of (dys)functional muscle cells and fibrotic tissue (the remains of dead cells) making it challenging to differentiate between native muscle defects and secondary tissue derived effects on overall tissue contractility such as stiffness and contractile function.        
One known method of cell force measurement using force transducers can be found in Addae-Mensah, K. A., Measurement Techniques for Cellular Biomechanics In Vitro, Minireview, Society for Experimental Biology and Medicine, p. 792-809, 2008.
It would be advantageous to provide instrumentation and methods for testing force and contraction in single cells, rather than groups of cells.